Two rods are connected as shown. The rods are of same length and same cross sectional area. In steady state, the  temperature $\left( \theta  \right)$ of the interface will be........ $^oC$

A black body at a high temperature $T\, K$ radiates energy at the rate $E\, watt/m^2$ ; when the temperature falls to $(T/2)\, K$ the radiated energy will be

Liquid cools from $50^oC$ to $45^oC$ in $5$ minutes and from $5^oC$ to $41.5^oC$ in the next $5$ minutes. The temperature of the surrounding is......... $^oC$

The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11\times10^{-5}\, cm$. According to Wien's law, the temperature of the source (on kelvin scale) will be n times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is $5.5\times10^{-5}\, cm$. The value of $n$ is

The figure shows a system of two concentric spheres of radii $r_1$ and $r_2$ and kept at temperatures $T_1$ and $T_2$, respectively. The radial rate of flow of heat in a substance between the two concentric spheres, is proportional to

A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling